On Fri, 13 Sep 2002, Dal Wheeler wrote:

>You might look at setting your pwm values with a lookup table if you want to
>have a smooth bloom and dim cycle.  LED's aren't linear on their percieved
>light output.  When I did them the table was more logrithmic.   I ran into
>this when working on a magic trick a few years ago...

The led light output is VERY linear with led current at a given junction
temperature, but your eyes aren't. Brightness does not mean the same thing
when used between normal humans and engineers ... the eye sensitivity is
logarithmic, so are most other human senses (like hearing and heat/cold
sense f.ex.).

A lookup table is not necessary if you use a power of 2 in the stepping.

Peter

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